Fatal Errors - Siemens SIMATIC S7 System Manual

Refer to the non-fatal error code list (Page 792) for a description of compile rule violations
and run-time programming problems.
Refer to the description of the SM bits (Page 799) for more information about the SM bits
used for reporting I/O and program execution errors.
5.7.2

Fatal errors

Fatal errors cause the PLC to stop the execution of your program. Depending upon the
severity of the fatal error, it can render the PLC incapable of performing any or all functions.
The objective for handling fatal errors is to bring the PLC to a safe state from which the PLC
can respond to interrogations about the existing error conditions.
When a fatal error is detected, the PLC changes to STOP mode, turns on the STOP and the
ERROR LED, overrides the output table, and turns off the outputs. The PLC remains in this
condition until the fatal error condition is corrected.
Once you have made the changes to correct the fatal error condition, use one of the
following methods to restart the PLC:
● Turn the PLC power off and then on.
● Using STEP 7-Micro/WIN SMART, click the "Warm Start" button in the modify area of the
PLC ribbon strip. This forces the PLC to restart and clear any fatal errors.
Restarting the PLC clears the fatal error condition and performs power-up diagnostic testing
to verify that the fatal error has been corrected. If another fatal error condition is found, the
PLC again sets the ERROR LED, indicating that an error still exists. Otherwise, the PLC
begins normal operation.
Some error conditions can render the PLC incapable of communication. In these cases, you
cannot view the error code from the PLC. These types of errors indicate hardware failures
that require the PLC to be repaired; they cannot be fixed by changes to the program or
clearing the memory of the PLC.
Refer to the fatal error code list (Page 796) for details.
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
Programming concepts
5.7 PLC error reaction
129